Caveat!!! Eclipse CDT 8.0 is REQUIRED for gnu x-tools seemingly. (That's Juno, Indigo I think... to we plebs) Grab it from Kek or Original software site.

Create the right project type (check the docs but in essence something c++ with make)

Create make targets

Open up the "Make Targets View" in Eclipse ("Window/Show View/Make Targets" — in my setup this is on the right part of the Eclipse window), click right-mouse on the project's name and add two new "Targets":